Monday, August 26, 2013

The acoustics of the Sydney Opera House

Growing up in Sydney in the 1960s (as I did) meant watching the politically ludicrous construction of the Sydney Opera House, a building now celebrating its 40th birthday. Indeed, in the late 1970s I went to a talk by Peter Hall, who had eventually taken over the design of the building interior, who said that the first job he was given was to decide exactly what shade of white the exterior tiles should be!

As was noted at the time of its completion: "It was a brilliant conception, but fatally flawed." In fact, it had, and still has, many flaws; but the one being referred to is the acoustics. Recently, in a ranking by Limelight magazine of 20 performance halls for classical music in Australia, ranked by the professionals who have to play in them repeatedly, the Concert Hall came 18th and the Opera Theatre came 20th (ie. dead last). [Note: The Sydney Opera House also has a Drama Theatre, and some other performance spaces, as well as the two large halls.]

Construction started in 1959 and was scheduled to be completed in 1963 at a cost of $A7 million. The building was finally opened in 1973 at a final cost of $A102 million. The New South Wales state government even had to institute a governmental lottery (the Opera House Lottery) to pay for it. I guess that this makes it as much a monument to successful gambling as to music.

The Opera House has since become iconic, of course, being one of the most recognized buildings in the world. It is now a UNESCO World Heritage Site, unlike the tram sheds that previously occupied the site (the Fort Macquarie Tram Depot). It has four resident companies: Opera Australia, the Australian Ballet, the Sydney Theatre Company, and the Sydney Symphony Orchestra. Visitors flock to the site, given its spectacular habour-side location; and Sydney would not be Sydney without it.

However, the complex has been plagued by problems as a performance venue. Indeed, the Sydney Theatre Company argued against using the Drama Theatre; and they eventually got their own theatre in a converted warehouse on the other side of the Sydney Harbour Bridge. The Opera Theatre has very cramped space for the orchestra. Moreover, the opera company cannot use sets from touring productions, because there are no wings to move scenery on and off the stage, necessitating one-off designs. Furthermore, many of the seats in the Concert Hall have very poor views.

But what is worst is that the acoustics in the two major halls are awful, and always have been.

In the Limelight ranking mentioned above, the Perth Concert Hall was the clear winner. It was built at the same time as the Sydney Opera House for a cost of $A3.2 million (the original budget was $A3.1 million). Sadly, the architectural style is what is commonly called Brutalist, which gives you some idea of what it looks like (the Sydney one is Expressionist). The important point, however, is that the Perth hall itself is shoe-box shaped, like almost all the great concert halls of the world, and unlike the Sydney ones.

Most of the Sydney problems stemmed from the original design, which was not a set of detailed plans as specified by the selection committee, but simply a series of conceptual drawings by the Danish architect Jørn Utzon. These drawings did not even match the original specifications. For example, the original brief specified a large hall for 3,000 people and a small hall for 1,200, but Utzon's acoustic plan had only 2,800 seats in the large hall, and even this was an over-estimate of how many could be fitted into his plan. Moreover, the building did not actually fit onto the specified site (a narrow peninsula sticking out into the harbour). Needless to say, the committee originally rejected the design out of hand; but they were over-ruled by outside circumstances (created principally by Eero Saarinen, a Finnish-born architect, who was at the same time involved in the design of the Trans World Flight Center at New York's John F. Kennedy International Airport, which not co-incidentally looks like a flattened version of the Opera House).

So, Utzon was given the job, and he turned out to be a very dogmatic person to work with. Indeed, he was eventually forced to resign (in 1966), but not before he had created many headaches for everyone else concerned. Ove Arup (the structural engineer) seems to have been the hero in dealing with Utzon's outrageous architectural demands. Peter Murray, in his history of the saga, notes:

Following Utzon's resignation, the acoustic advisor, Lothar Cremer, confirmed to the Sydney Opera House Executive Committee that Utzon's original acoustic design only allowed for 2,000 seats in the main hall and further stated that increasing the number of seats to 3,000 as specified in the brief would be disastrous for the acoustics.

Initially (1973), the poor acoustics were dealt with by suspending acoustic clouds (or donuts) from the ceiling, as shown in the photo above, apparently with small success. This was mainly so the performers could actually hear each other playing. Still, the conductor of the Sydney Symphony Orchestra, Edo de Waart, has since claimed that the Concert Hall has all the acoustics of a car park. [Note: Another Limelight magazine survey ranked the SSO as the clear winner among Australia's six state symphony orchestras, which makes its home in the SOH doubly ironic.]

So, what did the people of Sydney get for their money? A building that was 10 years late, cost 14 times as much as budgeted, had a capacity only 90% of what was asked, and with the worst acoustics in the country. I guess they are lucky that most people think it looks better than the tram-sheds ("it should be seen and not heard").

The acoustics were re-designed in 2009 (see Kirkegaard et al. 2010; Taylor & Claringbold 2010), but it is difficult to make major changes to a heritage building, even though it is being refurbished after 40 years, at an estimated cost of $A1,100 million.

The Fort Macquarie Tram Depot

The acoustics

It is therefore instructive to look at Utzon's original design presentation from March 1958, known as the Red Book, and the comments about the acoustics therein. Each design consultant (one each for structures, acoustics, mechanical services, electrical engineering, theatre techniques) prepared their own section of the book. The acoustics section was prepared by Vilhelm Lassen Jordan.

Of particular interest is the section entitled "Some Examples of Existing Large Halls and their Acoustic Data", which compares several characteristics (Volume, Number of seats, Volume per seat, Reverberation time empty, Reverberation time with audience) for seven existing concert halls, plus the proposed Sydney concert hall. As Jordan noted: "Satisfactory acoustics are based on a number of factors: reverberation time, sound distribution, sound diffusion and the overall dimensions." Of these, reverberation time was a key factor in the acoustics problems created by trying to fit the required number of seats into the hall as originally designed by Utzon.

I have analyzed the Red Book acoustic data using a phylogenetic network as a tool for exploratory data analysis. The analysis follows the same procedure as that for A network analysis of London's theatres. So, concert halls that are closely connected in the network are similar to each other based on their acoustic characteristics, and those that are further apart are progressively more different from each other.

The network clearly shows the claim being made in the 1958 Red Book — the new Concert Hall will be similar to the Concertgebouw, in Amsterdam, which is still rated as one of the top five halls in the world (see the ranking by Beranek 2003, 2004).

What a load of nonsense! In Leo Beranek's ranking of concert halls and opera houses throughout the world, the Sydney Opera House Concert Hall is ranked 53rd out of his 58 listed halls, whereas the Concertgebouw is ranked 5th. Something really went wrong, somewhere. Of the other halls shown in the network, the Göteborg Konserthus is ranked in a collection of equal halls at 21-40th, Usher Hall is 43rd, and Royal Festival Hall is 46th. (St Andrews Hall burnt down in 1962, and the two Danish halls are not listed by Beranek.) These rankings seem to be quite consistent with their relative locations in the network, except for the Sydney hall.

However, things are not always what they seem. It turns out that acoustic data do not always reflect the musical quality of a concert hall, as perceived by human ears. Beranek's ranking is based on the judgement of professional performers and music lovers, and we can quantitatively compare this judgement to various acoustic characteristics of most of the 58 ranked halls. Acoustical consultant Magne Skålevik has provided data for ten acoustic variables for 52 of the halls; and I have performed a network analysis of these data as well.

So, the network is based on the measured acoustic characteristics; and I have highlighted in red the top 11 ranked halls as rated by the listeners. Most of these top halls have similar acoustic qualities (ie. they cluster together in the network), with the Großer Musikvereinsaal, in Vienna, as the top ranker. Of these halls, eight were built before 1908 (the Großer Musikvereinsaal was built in 1870), which shows you how little we have learned recently about designing concert halls.

What is most interesting, however, is that the network shows that there are eight other halls with similar acoustic qualities to the top-ranked halls but with much lower rankings. These include the Tokyo Suntory Hall (ranked 17), Meyerhoff Symphony Hall (20), De Doelen Concertgebouw, Leipzig Gewandhaus, Kyoto Concert Hall, Tokyo Metropolitan Art Space, Christchurch Town Hall (all 21-40), and the Sydney Opera House Concert Hall (53). Apparently, there is more that meets the ear than can be measured by acoustic instruments.

I was also surprised to note that 7 of the bottom 15 ranked halls are in the U.K., although the only other two listed U.K. halls are ranked in the top dozen (St David's Hall, Cardiff, 10th; Colston Hall, Bristol, 12th).

What is also notable is that the reverberation time of almost all of the top-ranked halls is shorter than that of the Sydney Opera House Concert Hall (at 2.2 seconds). As Beranek (2004) notes: "For halls that generally feature standard orchestral repertoires ... the mid-frequency reverberation times should ... optimally [be] between 1.8 and 2.1 sec with the hall fully occupied." The Concert Hall thus reverberates for 0.2-0.3 seconds longer than the top-ranked halls, and this seems to be the ultimate source of its acoustic failure.

Architects design for clients, and either may have specific goals in mind. ... The architect may wish to build a monument that the public will travel far to see and that will win international awards. Either through lack of knowledge or interest, architects and owners may fail to build for, arguably, the most important feature of a hall for musical performance: how the acoustics of such a creation will or should sound.

Utzon built an architectural masterpiece, not a space for music performances.

Nowhere is Larsen's power to change a city's skyline on better display than in Copenhagen, where his Opera House dominates the waterfront, the undisputed icon of the harbor's transformation from a naval-industrial base to a cultural center. At half a million square feet and 14 stories, it is one of the city’s largest buildings ... It was Henning Larsen’s signature achievement, and, he later wrote, "my greatest failure." He thought it looked like a toaster.

Finally, it is worth noting that at the time of its construction the Sydney Opera House was architecturally unique (even given the TWA Flight Center, referred to above), but this is no longer so. In 1986, the Lotus Temple was opened in New Delhi, India, which has rather obvious similarities to the SOH, although it is much smaller (and has pools instead of a harbour). It was designed (starting in 1976) by Iranian-born architect Fariborz Sahba, who used three rings of nine shells each around a nine-sided dome to imitate a lotus flower (rather than imitating the boat sails that inspired Utzon). It is apparently more visited even than the Taj Mahal (3.5 million per year versus 3 million). I have no idea about its acoustics.

2 comments:

What a cool blog - and I learned a lot. By the way, the white tiles are spectacular whether watching the Australian Navy's 150th birthday celebrations projected on the sides of the Opera House; watching the annual New Year's Eve fireworks; or the Australia Day ferry boat races. Not sure what all that is going on outside might sound like from the inside though?!